Influence of cashew leaf ash as partial replacement for cement on the properties of fresh and hardened concrete

Abstract

Agricultural waste products generation are on the increase globally due to increase in agricultural activities to tackle food insecurity. However, the effective management of such waste remains a great challenge as the conventional disposal methods (open burning, landfilling and incineration) are becoming environmental threat. Thus, the Cashew Leaf Ash (CLA) effects as partial substitute for Portland cement (PC) on concrete properties was evaluated in this study. CLA was characterized through X-ray fluorescence analysis to ascertain its chemical composition. PC was substituted with 0 (control), 5, 10, 15, 20 and 25% CLA to produce six concrete batches of targeted design strength for grade 20 concrete. Fresh concrete was tested for slump and compacting factor to determine its workability. Furthermore, hardened concrete properties (density, compressive, split tensile and flexural strengths and water absorption) were investigated. The results revealed that CLA meets the requirements for application as supplementary cementitious material based on its chemical compositions. The workability and density declined with increase in CLA addition. The compressive, split tensile and flexural strengths of concrete containing CLA gradually decreased as the CLA contents with the exception of concrete with 5% CLA which showed higher strengths than the control at 90 days. The water absorption increased with increase in CLA addition but concrete with up to 5% CLA is within the permissible limit specified for good concrete. Furthermore, the proposed models from the experimental results were found to accurately predict the properties of CLA concrete when compared with the empirical models from selected codes. It was established that the optimum substitution of 5% CLA in PC is eco-efficient in concrete production.